API Reference
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Webhook endpoints
Download an attachment of a received email
GET
/v1/received_emails/{id}/attachments/{attachment_id}
The attachment's bytes, always as application/octet-stream (its declared type is the attachment's content_type): treat them as untrusted.
bearerAuthheader
AuthorizationBearer <token>A secret API key from the dashboard: coss_live_… for production environments, coss_test_… for sandbox environments.
id*stringThe received email's id.
attachment_id*stringThe attachment's id (from the received email's attachments).
Coss-Version?"2026-10-10"The API version (a date) to use for this request. Defaults to your organization's version, pinned to the latest one when it first used the API and upgraded from the dashboard. The SDK always sends the version it was built for.
Value in
"2026-10-10"The attachment.
response?fileapplication/octet-streamFormat
binaryimport { Coss } from "coss";const coss = new Coss({ apiKey: process.env.COSS_API_KEY, baseUrl: "https://api.coss.com",});const { data, error } = await coss.email.received.getAttachment("rcvd_01k7c8m4q2f3e9v6t5r1n0p8yz", "rcvdatt_01k7c8m4r0c2b8w9y3d5f6g7h8");"string"